Asset Impairments (Details) (USD $) In Millions, unless otherwise specified
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12 Months Ended |
3 Months Ended |
Dec. 31, 2014
MW
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Dec. 31, 2013
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Dec. 31, 2012
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Dec. 31, 2013
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Dec. 31, 2014
MW
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Sep. 30, 2014
MW
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Asset Impairments |
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Equity Method Investment, Ownership Percentage |
50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage |
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50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage |
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Impairment losses |
$ 97us-gaap_AssetImpairmentCharges |
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$ 459us-gaap_AssetImpairmentCharges |
$ 0us-gaap_AssetImpairmentCharges |
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Power Generation Capacity, Megawatts |
52,000.00nrg_PowerGenerationCapacityMegawatts |
[1] |
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52,000.00nrg_PowerGenerationCapacityMegawatts |
[1] |
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Indian River |
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Asset Impairments |
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Impairment losses |
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459us-gaap_AssetImpairmentCharges / us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis = nrg_IndianRiverMember |
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Coolwater [Member] |
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Asset Impairments |
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Impairment losses |
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22us-gaap_AssetImpairmentCharges / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nrg_CoolwaterMember |
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Power Generation Capacity, Megawatts |
636.00nrg_PowerGenerationCapacityMegawatts / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nrg_CoolwaterMember |
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636.00nrg_PowerGenerationCapacityMegawatts / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nrg_CoolwaterMember |
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Gladstone Power Station |
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Asset Impairments |
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Equity Method Investment, Ownership Percentage |
37.50%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nrg_GladstonePowerStationMember |
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37.50%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nrg_GladstonePowerStationMember |
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Impairment losses |
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92us-gaap_AssetImpairmentCharges / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nrg_GladstonePowerStationMember |
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Power Generation Capacity, Megawatts |
1,613.00nrg_PowerGenerationCapacityMegawatts / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nrg_GladstonePowerStationMember |
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1,613.00nrg_PowerGenerationCapacityMegawatts / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nrg_GladstonePowerStationMember |
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Noncontrolling Interest, Ownership Percentage by Parent |
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37.50%us-gaap_MinorityInterestOwnershipPercentageByParent / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nrg_GladstonePowerStationMember |
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37.50%us-gaap_MinorityInterestOwnershipPercentageByParent / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nrg_GladstonePowerStationMember |
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Osceola facility [Member] |
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Asset Impairments |
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Impairment losses |
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60us-gaap_AssetImpairmentCharges / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nrg_OsceolafacilityMember |
Power Generation Capacity, Megawatts |
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463.00nrg_PowerGenerationCapacityMegawatts / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nrg_OsceolafacilityMember |
Solar Panels [Member] |
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Asset Impairments |
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Impairment losses |
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$ 10us-gaap_AssetImpairmentCharges / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nrg_SolarPanelsMember |
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